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Poly(p-phenylene oxide)

Poly(p-phenylene oxide) (PPO) or poly(p-phenylene ether) (PPE) is a high-temperature thermoplastic. It is rarely used in its pure form due to difficulties in processing. It is mainly used as blend with polystyrene, high impact styrene-butadiene copolymer or polyamide.

History

Polyphenylene ether was discovered in 1956 by Allan Hay, and was commercialized by General Electric in 1960. The common name “polyphenylene oxide (PPO)” is incorrect because it is not an oxide but an ether.

While it was one of the cheapest high-temperature resistant plastics, processing was difficult and the impact and heat resistance decreased with time. Mixing it with polystyrene in any ratio could compensate for the disadvantages. In the 1960s, modified PPE came into the market under the trade name Noryl.

Properties

PPE is an amorphous high-performance plastic. The glass transition temperature is 215 °C, but it can be varied by mixing with polystyrene. Through modification and the incorporation of fillers such as glass fibers, the properties can be extensively modified.

Applications

A printer cartridge made of PPE and polystyrene; it is an example of a product which requires good dimensional stability and accuracy to fit.

PPE blends are used for structural parts, electronics, household and automotive items that depend on high heat resistance, dimensional stability and accuracy. They are also used in medicine for sterilizable instruments made of plastic.

This plastic is processed by injection molding or extrusion; depending on the type, the processing temperature is 260-300 °C. The surface can be printed, hot-stamped, painted or metallized. Welds are possible by means of heating element, friction or ultrasonic welding. It can be glued with halogenated solvents or various adhesives.

Production from natural products

Natural phenols can be enzymatically polymerised. Laccase and peroxidase induced the polymerization of syringic acid to give a poly(1,4-phenylene oxide) bearing a carboxylic acid at one end and a phenolic hydroxyl group at the other.